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Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Yanping Chen

,

Runfang Xiang

,

Fuyang Cao

,

Lunyong Zhang

,

Jianfei Sun

,

Hongxian Shen

,

Daoli Qu

,

Haichao Li

Abstract: Al-Zn-Mg-Cu-Zr alloys are widely utilized in aerospace applications; however, their strength typically remains below 800 MPa, insufficient for growing industrial demands. This research therefore aims to enhance their mechanical properties by investigating the effects of heat treatment on both performance and microstructure. The research utilized experimental investigations to resolve the problem. To prepare 800 MPa-grade Al-Zn-Mg-Cu-Zr alloys, the effects of different heat-treatment methods on the microstructure and properties of the alloys were investigated. The results show that the hardness during single-stage aging exhibits a double peak characteristic, and the peak aging time of the Al-Zn-Mg-Cu-Zr alloy was 18 h. The alloy grain size follows the order: peak aging < over-aging < double aging < retrogression and re-aging (RRA). The grain boundary precipitates gradually evolved from a continuous network in the peak-aged condition to a coarsened and discontinuous distribution. The tensile strength of the alloy was ranked as follows: peak aging > RRA > over aging > double aging, whereas the elongation followed the order: RRA > peak aging > double aging > over aging. The RRA aging treatment provided the greatest improvement in the overall properties of the Al-Zn-Mg-Cu-Zr alloy, whereas the peak aging treatment yielded the highest tensile strength.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Jonathan Josué Cid-Galiot

,

Alberto Alfonso Aguilar-Lasserre

,

José Pastor Rodriguez-Jarquin

,

José Ernesto Domínguez Herrera

,

Isaí Pardo-Escandón

Abstract: Aged pipeline networks are exposed to interacting operational, electrochemical, structural, and metallurgical degradation mechanisms that are commonly assessed independently, limiting the diagnosis of system-wide failure propagation. This study develops an integrated and interpretable fuzzy-logic framework for detecting, quantifying, and isolating failure scenarios in a 572 km pipeline transportation network. The methodology combines approximately 2.5 million historical SCADA and SAP records, cathodic-protection and soil measurements from 89 evaluation points, 5661 ultrasonic-inspection anomalies, mechanical and metallographic characterization of API L X65 steel, and validated expert knowledge. Four Mamdani fuzzy inference systems were constructed to represent operational capacity, cathodic-protection performance, mechanical integrity, and metallurgical degradation. Their outputs were integrated into a unified fault-signature matrix comprising 28 failure scenarios. Scenario FS-3 produced the broadest systemic response by activating all diagnostic residuals, whereas metallurgical scenarios FS-22 – FS-28 activated 61% of the matrix, indicating their extensive influence on pipeline integrity. Structural scenarios FS-15 – FS-21 exhibited progressively broader signatures as wall deterioration increased, while FS-1, FS-2, FS-5, FS-6, and FS-7 remained localized and were more readily isolated. The proposed framework preserves diagnostic traceability through explicit input variables, fuzzy rules, and residual signatures, providing an interpretable basis for failure classification, Diagnostic signature breadth, maintenance prioritization, and operator decision support. Its conclusions are limited to the analyzed network and require external validation before application to other pipeline systems.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

S Kumar Reddy Mallidi

,

Tejinder Kaur

,

Ankita Chhikara

,

D. Rosy Salomi Victoria

,

Krishnanjaneyulu Payala

Abstract: Predicting yield strength (YS), ultimate tensile strength (UTS), and elongation (El) in heat-treatable aluminum alloys is challenging because of nonlinear interactions between alloy composition and heat-treatment parameters. This study proposes a physics-retained, explainable, and uncertainty-aware multi-target machine-learning framework for simultaneous strength–ductility prediction. A hybrid feature-selection strategy combining statistical relevance, mean embedded importance, and metallurgical retention reduced the input space from 17 to 12 variables while preserving solution treatment temperature, aging temperature, and aging time. A matched 17-feature comparator was evaluated using the same repeated outer-validation splits, inner tuning procedure, model families, hyperparameter-search space, and search budget. Across 25 outer evaluations, the 12-feature pipeline achieved a macro-averaged R2 of 0.807 ± 0.043, macro-NRMSE of 0.424±0.047, and macro-NMAE of 0.293 ± 0.033, compared with 0.800 ± 0.047, 0.431 ± 0.052, and 0.294 ± 0.040, respectively, for the 17-feature pipeline. An exploratory post-selection paired comparison yielded a mean macro-R2 difference of 0.0068, a corrected 95% interval of [−0.0198,0.0335], and p = 0.602. Because k = 12 was selected using the same outer-validation summaries, these statistics are descriptive rather than confirmatory. The selected pipeline therefore used 29.4% fewer descriptors with similar observed mean performance, although superiority or statistical equivalence was not established. On the untouched final-test partition, the locked 12-feature ExtraTrees model achieved target-wise R2 values of 0.857, 0.842, and 0.826 for YS, UTS, and El, respectively. SHAP assigned the largest model attributions to Zn, Cu, and selected heat-treatment conditions; these attributions explain model behavior rather than causal metallurgical effects. Ensemble-conformal intervals supported uncertainty-aware retrospective prioritization of held-out conditions. However, because no external or experimental validation was performed and performance decreased under composition-group-disjoint validation, the framework should be regarded as an internally evaluated modeling workflow rather than a validated alloy-design tool.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Senlin Li

,

Ningwei Zuo

,

Jinbao Zhang

,

Xueqiang Yang

,

Yuxuan Sun

Abstract: Beryllium-tungsten (Be-W) intermetallic compounds with low density, high elastic modulus, high melting point, and outstanding irradiation and corrosion resistance are promising candidates for extreme-environment applications, including fusion reactor plasma-facing components, aerospace high-temperature structures, and nuclear reactor functional materials. Herein, first-principles calculations based on the density functional theory (DFT) plane-wave pseudopotential method were performed to systematically explore the crystal structure, thermodynamic stability, electronic structure, bonding characteristics, and mechanical properties of three typical Be-W intermetallics (Be2W, Be12W, and Be22W). The consistency between optimized lattice parameters and experimental data validates the accuracy of the computational model. The calculated results reveal that Be12W has the lowest formation enthalpy and superior phase-forming capability, whereas Be2W presents the highest cohesive energy and Fermi level density of states, corresponding to inferior thermodynamic stability. All three intermetallics are mechanically stable and intrinsically metallic, with chemical bonding primarily governed by strong Be-p–W-d orbital hybridization and distinct covalent features. Mechanically, Be2W exhibits excellent volumetric deformation resistance, Be12W achieves the highest shear and Young’s moduli with optimal comprehensive mechanical performance, and Be22W possesses relatively poor mechanical properties. This work elucidates the inherent correlations between the structural, electronic, thermodynamic, and mechanical behaviors of the Be-W system, offering reliable theoretical guidance for the composition optimization, phase control, and fabrication design of advanced B-W based high-temperature irradiation-resistant structural materials.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Joana Quaresma

,

João Pimenta

,

Luis Alves

,

Fábio Ferreira

,

José Góis

,

Ricardo Mendes

Abstract: Al-NiO thermites are recognized for their high energy density, low gas emission, and stable at normal conditions, making them ideal for applications requiring high concentrated heat. This study investigates the influence of three physical mixing techniques—mortar-pestle, magnetic stirring, and ball milling—on the morphology, reactivity, and thermal behaviour of Al-NiO thermites under different heating rates (20, 35, 50 oC/min). Advanced characterization techniques, including SEM/EDS, particle size distribution (PSD) analysis, zeta potential (ZP), DSC/TGA, and electrothermal ignition tests, were employed. The results reveal that ball milling significantly reduces particle size to the nanoscale and enhances ignition properties, despite limited improvements in homogeneity due to agglomeration tendencies. Thermal analyses showed that, while all techniques produced good thermal properties, the ball-milled thermite demonstrated activation energy and ignition characteristics consistent with nanoscale systems. Faster heating rates revealed distinct morphological outcomes and reaction pathways among mixing techniques. Importantly, this study demonstrates that cost-effective mixing methods can still yield thermites with promising thermal and ignition properties, suggesting their potential for scalable industrial applications. These findings contribute to optimizing Al-NiO thermites for advanced energetic systems in both civilian and military domains.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Xinhai Zhao

,

Xinghui Wang

,

Chao Zheng

,

Liangang Zhao

Abstract: Point to the manufacturing process of variable-section rectangular tube, a four-die radial extrusion process was designed in this article. The general deformation law was researched in two-dimensions, the influence of deformation parameters on the deformation results was explored, and the method by using the mold anti-deformation to eliminate the concave defects was proposed. For the tube parts with common thickness to diameter ratio, the corresponding optimal die arc degree is obtained through simulation and optimization. After that, the two-dimensional deformation law is applied to three dimensions, and the methods to eliminate the defect are carefully studied and successfully realized. Taking a variable-section rectangular tube as an example, the experiment was carried out. The experimental results were compared with the simulation results, and the accuracy of the simulation results and the feasibility of the process were verified.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Hongyang Wang

,

Wenxuan Mo

,

Kai Dong

Abstract: Dephosphorisation in oxygen steelmaking depends on more than the equilibrium phosphorus partition ratio. It also depends on where gas, slag, metal and injected lime powder coexist while the bath is being stirred. We develop a gas–slag–metal–particle reaction model for bottom-blown oxygen–CaO powder injection by coupling Euler–Euler transport of liquid steel, mixed slag and gas with discrete CaO-particle motion. The local source terms include oxygen dissolution, FeO/Fe2O3 conversion, CO/CO2 buffering, competitive C/Si/P oxidation, P2O5 formation, C2S–C3P fixation, reaction heat and phase-wise mass conservation. Instead of resolving every bubble or slag droplet, the model represents bubble swarms, dispersed slag and emulsified metal–slag contact through mean-field interfacial area densities tied to local phase fractions and mixing. Two cases with the same initial phosphorus content but different carbon levels are used to test reaction selectivity. In the high-carbon bath, bottom-blown oxygen is consumed first by decarburisation; the generated CO sustains plume buoyancy but reduces FeOx retention during flotation. CaO addition improves local slag formation, but it contributes to dephosphorisation only where FeOx supply, P2O5 generation and C2S–C3P fixation coincide at an active slag–metal interface. The stable dephosphorisation window therefore lies mainly in the upper slag–metal mixing zone, not in the bottom gas column. The model provides a computable basis for analysing bottom powder injection, combined blowing and low-carbon endpoint dephosphorisation in gas–slag–metal reactive flows.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Han Hu

,

Ziqiang Dong

,

Yanjie Liu

,

Yi Liu

Abstract: Cu-based interpenetrating phase composites (IPCs) represent a paradigm for sliding electrical contacts where the synergy between thermal management, wear resistance, and electrical transport is critical. Herein, we engineer Cu-(CrWₓ)C IPCs (x = 0, 10, 25, 50 wt%) via pressureless infiltration, elucidating a tungsten-mediated architectural stabilization mechanism. We demonstrate that controlled W incorporation refines the carbide skeleton, optimizing the load-transfer efficiency between the rigid ceramic network and the continuous Cu-rich functional phase. Microstructural characterization (XRD, SEM/EDS) confirms the intact three-dimensional interpenetration, with higher W content promoting the segregation of W-rich domains. Quasi-static compression (10-3 s-1) validates the structural robustness under large-strain regimes. Notably, all composites retain high electrical conductivities (~39–41 % IACS); the Cu-(CrW10)C variant exhibits the peak thermal conductivity at 500 °C. Tribological evaluations reveal that optimal wear resistance is decoupled from peak hardness; instead, it arises from the stabilization of a skeleton-supported tribo-damaged layer facilitated by moderate W addition. Conversely, excessive W enrichment induces brittle fragmentation and interfacial debonding, exacerbating third-body abrasion. Quantitative analysis using a Thermo-Tribological Performance Index (TTPI) and an Electrical-Thermal-Wear Balance Index (ETWBI) confirms that Cu-(CrW10)C achieves the optimal equilibrium among material removal resistance, heat dissipation, and dimensional stability. This work establishes a design strategy for high-performance IPCs by leveraging architectural tuning to reconcile traditionally conflicting property requirements.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Aijun Li

,

Jun Ma

,

Jianzhong Wang

Abstract: Sintering diagram for copper fibers is established based on a two joint-fiber geometric model and intrinsic material constants, with comprehensive consideration of four neck-growth mechanisms: volume diffusion, grain-boundary diffusion, surface diffusion and Nabarro-Herring microcreep. The sintering diagram reveals that grain-boundary diffusion dominates neck growth at relatively low temperatures, surface diffusion prevails at high temperatures for short holding time, and Nabarro-Herring microcreep acts as the primary mechanism at high temperatures for long holding time, respectively. In addition, synchrotron radiation X-ray computed tomography (SR-CT) characterization is adopted to validate the established sintering diagram via the measured neck size of sintered fiber joints. The experimental results show that most measured neck-size data points lie close to the theoretical curve predicted by the Nabarro-Herring microcreep mechanism when sintered at 1030 oC for 30 min, 60 min and 180 min. This result confirms that Nabarro-Herring microcreep is the predominant neck-growth mechanism at high temperatures for long holding time, which is consistent with the theoretical result derived from the sintering diagram. Meanwhile, the results also prove the existence of Nabarro-Herring microcreep during the high-temperature sintering of copper fibers without externally applied pressure.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Florentina Niculescu

,

Mariana-Mirela Stănescu

,

Gheorghe Iacob

,

Adrian Onici

,

Lenuta Zidaru

Abstract: This article analyzes in detail the structural, thermal and mechanical properties of the Ni₅₄Cr₂₈Mo₈Nb₅Ta₅ alloy, as well identify potential applications in areas where exceptional high-temperature performance is required — such as gas turbines, nuclear reactors or aeronautical engine components. Obtaining a very good correlation between the experimental and fitted profiles, as well as the low values of the error parameters (R-factors), confirms the accuracy of the structural model and the validity of the phases identified following the XRD analysis. The study also aims to highlight the relationship between chemical composition, microstructure and mechanical behavior, providing a basis for optimizing heat treatments and manufacturing processes of this advanced superalloy.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Arkapol Saengdeejing

,

Ryoji Sahara

,

Yoshiyuki Kawazoe

,

Kazuyuki Higashino

Abstract: Platinum-Rhodium alloys are one of the prominent alloys used in the high temperature and high corrosion environment. Due to the nature of Pt and Rh, it maintains the single solid solution phase up to very high temperature. In order to develop and design a new part to be used in the field, many techniques, tools, software in combination are needed. Phase field method (PF) is used for microstructure prediction or finite element method (FEM) for stress analysis. Those methods require additional data such as thermodynamic stability for PF and elastic modulus for FEM. Pt-Rh binary system, the experimental data for thermodynamic stability and elastic properties are very limited and mostly available only for pure elements. In this work, we performed first-principles calculations to predict the temperature dependent elastic properties of fcc-disordered PtRh alloys at various concentrations. The special quasirandom structures (SQS) are used to describe the disordered structure of fcc-disordered PtRh alloys. Vibrational contribution to the free energy are performed with the quasi-harmonic phonon approximation to obtain the finite-temperature free energy and coefficient of thermal expansion for the fcc-disordered PtRh alloys. The elastic stiffness of the fcc-disordered PtRh alloys at different concentrations are obtained through the energy-strain method. By coupling between calculated coefficient of thermal expansion and the elastic stiffness data calculated at various volumes, the finite-temperature elastic stiffness of the fcc-disordered PtRh alloys can be obtained.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Changming Fang

,

Zhongping Que

,

Zhongyun Fan

Abstract: Commercial aluminum (Al) metals contain unavoidably iron (Fe) and silicon (Si) as impurities. Due to its low solubility and high chemical affinity to Al, Fe exists in the form of Fe-containing intermetallic compounds (Fe-IMCs) which act crucially in solidification processes, determining the micro-structure and consequently the mechanical performance of the cast parts. Meanwhile, Si as impurity or addition may join the binary Fe-IMCs. Here, we investigate the Si stabilization effects on the frequently observed Al-rich Fe-IMCs in a comprehensive and systematical way using a first-principles density-functional theory (DFT) approach. The study revealed different Si stabilization effects on the cubic α- and hexagonal αʹ-phase, as well as other binaries: Al12Fe, η-Al6Fe, τ4-, β- and θ-phases. The enhancement of stability for the α-phase is moderate while it is strong for the αʹ-phase. For the stability series (from higher to lower) is θ-Al13Fe4 > η-Al6Fe >α-Al4.75Fe in the binary system, while it becomes τ4-(Al,Si)5Fe>β-Al4.5SiFe >αʹ-(Al,Si)4.174Fe for the ternary Fe-IMCs. The information obtained here helps understand the formation of Fe-IMCs particles during casting of Al-Si alloys, and design of novel Al alloys of fine micro-structures and desired mechanical performances of the products from the primary Al and the scraps and wastes.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Tong Wu

,

Shuming Xing

Abstract:

In this paper, the supersaturated solid solution of Al-Cu3-Si-Mg alloy prepared by molten metal die forging (MMDF) was used as the research object. The formation and evolution of precipitates during aging treatment were investigated through experiments at different temperatures and times, and the precipitation mechanisms and sequences of various precipitates were analyzed. The main precipitated phases formed in the supersaturated solid solution of Al-Cu3-Si-Mg alloy after aging treatment are θ(Al2Cu), θ'(Al3.6Cu2), γ'(Al0.63Mg0.37) and η'(Cu, Si). Based on XRD and TEM analysis under different aging treatment conditions, the precipitation sequence is determined as follows: SSS GP0 GP0+γ'→GP0+(γ'+γ)+θ''+η'→(γ'+γ)+(θ''+θ')+(η'+η)→(γ'+γ)+(θ+θ')+(η'+η)→(γ'+γ)+(θ+θ')+η→γ+θ+η. With increasing aging temperature and time, precipitates tend to accumulate at the α-Al grain boundaries. After aging treatment at 165-185 °C for 4 h, chain-like θ(Al2Cu) precipitates are discontinuously distributed at the α-Al grain boundaries, disk‑shaped θ'(Al3.6Cu2) and θ''(Al2Cu) phases mainly precipitate within the grains. When the temperature exceeds 185 °C, the chain-like θ(Al2Cu) precipitates at the grain boundaries gradually become continuous, the amount of θ(Al2Cu) phase in the grains increases significantly, θ''(Al2Cu) disappears completely, and the size of θ'(Al3.6Cu2) decreases obviously. After aging treatment at 185 °C for 5-6 h, the chain-like θ(Al2Cu) precipitates at the grain boundaries become more continuous, and their length fraction continues to increase with prolonged aging time.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Alotaibi Fawaz Marzouq S

,

Usman Ali

,

Atta-Ur Rehman

,

Talal Ameen Ali Alhemyari

Abstract: This study investigates the microstructural evolution and mechanical behavior of a Ni-based superalloy subjected to combined heat treatment and laser processing. Special emphasis is placed on the quantitative analysis of γ′ Ni3(Al,Ti) and η (Ni3Ti) phase distributions using SEM-based statistical methods. OM/XRD were employed for initial structural and phase identification, followed by detailed microstructural characterization using SEM/EDS. The results reveal that γ′ precipitates exhibit a fine and uniform distribution with a high number density, whereas the η (Ni3Ti) phase appears as relatively coarse and sparsely distributed particles. Statistical size distribution analysis demonstrates that processing parameters significantly influence precipitate morphology and phase stability. Laser treatment promotes redistribution of γ′ precipitates and suppresses η (Ni3Ti) phase formation, resulting in improved microstructural homogeneity. Mechanical characterization shows a strong correlation between γ′ Ni3(Al,Ti) phase refinement and enhanced hardness and tensile properties. Fractography analysis indicates predominantly ductile fracture behavior with microvoid coalescence. The findings provide a quantitative understanding of phase evolution and establish a microstructure property relationship for optimizing Ni-based superalloys through advanced processing techniques.

Review
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Yi Qiao

,

Yong Zhang

Abstract: Since its introduction, focused ion beam (FIB) technology has expanded from micro/nanofabrication in the semiconductor industry into the field of multimodal characterization of metallic material microstructures. This article systematically reviews the latest research advances of FIB-SEM technology in the field of metallic materials science. The fundamental principles and system functions of FIB-SEM are introduced, with emphasis on its key applications in two-dimensional and three-dimensional morphological characterization, as well as specimen preparation for transmission electron microscopy (TEM) and atom probe tomography (APT). The combined strategies of FIB-SEM with electron backscatter diffraction (EBSD), time-of-flight secondary ion mass spectrometry (TOF-SIMS), and other characterization techniques are also discussed. Current developments indicate that FIB-SEM technology is advancing toward multi-ion-source synergy and multimodal integration. In the future, combined with artificial intelligence and big data analysis, it is expected to enable high-throughput, correlative measurements of multidimensional properties at the micro-scale, providing important technical support for "materials genome" research in metallic materials.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Majid Ramezanpour Aghdami

,

Ashkan Mohammad Beygian

,

Eskandar Keshavarz Alamdari

Abstract: Copper anodic slime is a valuable secondary resource for precious and critical elements such as gold, silver, selenium, and tellurium. In certain industrial flowsheets, copper anodic slime is smelted together with lead to facilitate silver and gold recovery, generating a fine lead‑rich fly ash as a secondary residue. This dust contains considerable amounts of selenium and tellurium and poses significant environmental and occupational health risks due to its high lead content and sub‑micron particle size. The present study investigates sodium carbonate (Na₂CO₃) leaching as an environmentally benign pre‑treatment approach aimed at partial removal of selenium and tellurium while simultaneously stabilizing lead through carbonate formation. Rather than targeting maximum metal recovery, the process is evaluated from a detoxification‑oriented perspective suitable for safer disposal or downstream recycling of hazardous metallurgical dusts. The effects of sodium carbonate concentration, temperature, solid‑to‑liquid ratio, and leaching time on selenium and tellurium recovery were investigated using a central composite design (CCD) implemented in Design‑Expert software. Under the investigated conditions, selenium recovery reached a maximum of 53.9%, while tellurium recovery remained generally below 15%, with a maximum observed value of approximately 33.9% in a specific experimental run. Scanning electron microscopy revealed that the dust consists primarily of semi‑spherical and elongated particles, with lead carbonate precipitation occurring preferentially on particle surfaces during leaching. Energy‑dispersive spectroscopy confirmed the conversion of lead sulfate phases to lead carbonate, which progressively limited further selenium and tellurium dissolution. A brief kinetic analysis indicated that selenium dissolution follows a mixed control regime involving surface chemical reaction and diffusion through product layers, whereas tellurium leaching did not exhibit consistent kinetic behavior across the studied conditions. The results demonstrate that sodium carbonate leaching can effectively reduce the mobility of selenium and tellurium while stabilizing lead, supporting its application as a detoxification‑oriented pre‑treatment for lead‑rich metallurgical dusts rather than a conventional high‑recovery extraction process. Furthermore, thermodynamic analysis confirmed the environmental detoxification of the residue through the stable immobilization of lead as cerussite (PbCO3). The macroscopic dissolution behavior was successfully described using an apparent Shrinking Core Model (SCM), revealing the interactive effects of leaching parameters on the kinetic bottlenecks.

Essay
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Xiaoqi Zhang

,

Jinhao Li

,

Chengxian Yuan

,

Long Wang

,

Zhongliang Gao

Abstract: Resistance spot welding of dissimilar steels is a key Linkage process in the manufacturing of rail passenger car bodies. However, there are problems such as core deviation caused by material physical property differences in the welding of dissimilar steels (stainless steel/low-carbon steel). This study improves the weldability of stainless steel and low-carbon steel by adding a nickel intermediate layer between them. The results show that adding a nickel intermediate layer can Valid compensate for heat Loss, suppress the deviation of the weld nucleus, optimize the size of the weld nucleus, and improve the Stability of the welding quality.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Lixin Fang

,

Liqin Qin

,

Limin Zhang

,

Hao Zhou

,

Xudong He

,

Zekun Ren

,

Tongyi Zhang

,

Yi Liu

Abstract: Machine learning interatomic potentials (MLIPs) are typically constructed for homogeneous crystalline systems that exhibit only minimal local deviations from equilibrium configurations. However, substitutional alloying elements in multicomponent engineering alloys are often distributed in a locally heterogeneous form. To address this, we develop a fine tuned MLIP based on the MACE foundation model, specifically tailored for Mo based dilute alloys containing one or two out of 20 substitutional elements: Cr, Fe, Mn, Nb, Re, Ta, Ti, V, W, Y, Zr, Al, Zn, Cu, Ag, Au, Hg, Co, Ni, and Hf. The model is trained on more than 7,000 non equilibrium structures derived from first principles density functional theory (DFT) calculations. The optimized large scale fine tuned model attains state of the art accuracy, with mean absolute error (MAE) and root mean square error (RMSE) of 2.27 meV/atom and 3.79 meV/atom for energy predictions, and 13.83 meV/Å and 24.26 meV/Å for force predictions, respectively. Systematic evaluation of model transferability to unseen alloying elements under different data splitting protocols demonstrates that incorporating even a modest set of new element DFT data during refinement reduces the energy MAE below ~20 meV/atom. The fine tuned models reduce the MAE by approximately 7–10 times compared to models trained from scratch, and by 10–20 times relative to zero shot foundation models. This performance gain remains consistent across varying dataset sizes (equilibrium vs. non equilibrium structures) and model scales. Our work illustrates the efficacy of transfer learning from globally homogeneous systems to locally heterogeneous multi element alloy environments, delivering a robust MLIP tool for the accelerated design of multicomponent alloys.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Xiaoshan Liu

,

Anping Long

,

Haijie Zhang

,

Dexin Ma

,

Min Song

,

Menghuai Wu

,

Jianzheng Guo

Abstract: This paper investigates the formation mechanism and key influencing factors of freckle defects that arise during the directional solidification of a novel third-generation nickel-based single crystal superalloy turbine blade. A combined experimental and multi-physics numerical simulation approach was adopted. The results reveal that freckle formation primarily results from the coupling effect of solute segregation and thermo-solutal convection during solidification, leading to dendrite fragmentation and subsequent aggregation of equiaxed grains. The resultant density inversion drives upward interdendritic flow, which plays a dual role: it promotes remelting and fragmentation of secondary dendrite arms, while simultaneously opening solute-enriched preferential flow channels that eventually develop into freckle defects. The severity of freckling is closely dependent on both the casting's position within the furnace and its local geometric characteristics. Castings located in regions with poorer heating conditions experience lower temperature gradients and slower solidification rates, significantly increasing their susceptibility to freckle formation. Similarly, on a given casting, the side subjected to less favorable heating is more prone to freckle initiation. This work provides a crucial theoretical foundation for understanding freckle formation in nickel-based single crystal superalloys and offers practical guidance for optimizing blade manufacturing processes, reducing solidification defects, and enhancing blade quality and service performance.

Article
Chemistry and Materials Science
Metals, Alloys and Metallurgy

Xiuda Zhu

,

Changle Xiao

,

Xiubin Wang

,

Xiaohu Chen

,

Hongyan Wu

,

Wei Chen

Abstract:

This study systematically investigates the effects of the final annealing temperature on the microstructural evolution and mechanical properties of an Al-Fe-Si alloy aluminum foil. Scanning electron microscopy (SEM) characterization and tensile tests are employed for analysis. As the annealing temperature is elevated from 240°C to 360°C, the average grain size increases monotonically from 5.2 μm to 9.6 μm. Continuous recrystallization is identified as the predominant grain growth mechanism.Tensile deformation exhibits the homogeneous-plastic behavior without localized necking. The tensile strength decreases significantly in the range of 240–300°C and subsequently undergoes a recovery stage at 300–360°C. The Pronounced elongation anisotropy is observed. The maximum elongation reaches 30–34% along the 45° direction relative to the rolling direction (RD), which is approximately 1.5 times that along the RD (0°).Comparative analysis of the anisotropy indices demonstrates that the aluminum foil annealed at 240°C achieves the minimal tensile strength anisotropy (13.0 MPa) and elongation anisotropy (−4.2%). This indicates optimal comprehensive mechanical performance.These findings provide a theoretical rationale for the industrial optimization of the annealing processes for Al-Fe-Si alloy foils. They are particularly valuable for balancing microstructural regulation and mechanical property enhancement in lithium-ion battery soft-packaging applications.

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